Cutoff assembly for use at wellheads



PYl 23, 1968 A. l.. BURNS, JR`.. ETAL 3,379,255

CTOFF ASSEMBLY FOR USE AT WELLHEADS 2v Sheets-Sheet 1 Fild July 28, '196e /IT'I'ORNE YS April 23, 1968 A. L. BURNS, JR.. Ew. 3,379,255

CUTOFF ASSEMBLY FOR USE AT WELLHEADS Filed July 28, 1966 2 Sheets-Sheet '2 United States Patent O 3,379,255 CUTOFF ASSEMBLY FUR USE AT WELLHEADS Albert L. Burns, Jr., and Damon T. Slater, Houston, Tex., assignors to Bowen Tools, Inc., a corporation of rTexas Filed .Iuly 28, 1966, Ser. No. 568,456 Claimse (Cl. 16S-55) This invention relates to new and useful improvements in cutoff assemblies for use at wellheads, and particularly an assembly for cutting a well pipe or the like at the wellhead.

An object of the present invention is to provide a new and improved apparatus for use at the wellhead, wherein a well pipe or the like is effectively cut in half by such apparatus when necessary or desirable.

Another object of this invention is to provide a new and improved wellhead apparatus having a cutoff mechanism for cutting a well pipe or the like and a biowout preventer for closing off the annuius around the well pipe above the point of cutting to prevent a blowout of the well.

The preferred embodiment of this invention will be described hereinafter, together with other features thereof, and additional objects will become evident from such description.

The invention will be more readily understood from a reading of the following specification and by reference to the accompanying drawings forming a part thereof, wherein an example of the invention is shown, and wherein:

FIG. 1 is an elevation of the apparatus of this invention in the preferred form;

FIG. 2 is a vertical sectional view of the left-hand portion of the apparatus illustrated in FIG. l, with the parts of the cutoff assembly and the blowout preventer in the retracted positions;

FIG. 3 is a vertical sectional view, partly in elevation, illustrating portions of the apparatus illustrated in FIG. 1, with the parts of the cutoff assembly and the blowout preventer in the operating or inner positions; and

FIG. 4 is a partial exploded view of a portion of the cutoff assembly to further illustrate the details of the preferred form of the invention.

In the drawings, the letter A designates generally the apparatus of this invention (FIG. 1) which includes a blowout preventer B and a cutoff assembly C in the preferred form of the invention. The apparatus A is adapted to be mounted at the wellhead so that a well pipe or tubing T (FIGS. 2 and 3) may be fed therethrough under normal operating conditions. In the event it becomes desirable to cut or sever the tubing T, the apparatus A may be actuated so as to cause the cutoff assembly C to sever the tubing T (FIG. 3) and the blowout preventer B to close the well. As will be more evident hereinafter, the cutoff assembly C is a unique construction which provides for the gripping or holding of the pipe T to stabilize same during the cutting action.

Considering the invention more in detail, the apparatus A of this invention includes a housing which is preferably formed in a plurality of parts as illustrated in detail in FIGS. 2 and 3. Thus, the housing includes a longitudinally extending body 1t) which has a longitudinal bore 10a therethrough, through which the tubing T or other elongate element is adapted to extend during normal well operations. The body 10 is provided with lower threads 10b for securing the apparatus A in position on the usual wellhead equipment. Threads 10c are provided at the upper end of the body 10 for connecting additional equipment such as a lubricator thereabove. The housing also includes four cylinders 15, 115, 16, and 116 (FIGS. 2 and 3). Such cylinders 15, 115, 16, and 116 extend laterally or perpendicularly from the longitudinal body and are preferably made up of a plurality of components as illustrated in the drawings. The cylinders and 115 are diametrically opposed to each other and form the cylinders of the cutoff assembly C. The cylinders 16 and 116 are diametrically opposed to each other and form the cylinders of the blowout preventer B.

To facilitate consideration of the details of the cutoff assembly C, reference is now made to the left-hand p0rtion of such structure which is shown in detail in FIG. 2, the portions of which are also shown in FIGS. 3 and 4. A rst piston 20 is slidably disposed in the cylinder 15 and it has an indicator rod 21 extending therefrom through a suitable opening 15a so that the position of the piston 20 and the parts operably connected therewith may be readily observed from externally of the cutoff assembly C, as will be more evident hereinafter. The rod 21 may be secured to the piston 20 by threads 21a or any other suitable connecting means. The piston 20 is provided with an O-ring 22 formed of rubber or other resilient material for sealing engagement with the cylinder bore 15b during sliding or longitudinal movement of the piston 20 relative lo the cylinder 15. A shoulder 20a is provided on a forward face of the piston 20 for engagement by a coil spring 23 formed of spring steel or other suitable resilient material, such spring 23 also engaging a laterally-extending annular shoulder 15C in the cylinder 15 so that such spring 23 exerts a return force tending to move the piston 20 in a direction from the longitudinal bore 19a of the body 10. An annular seal 24 formed of rubber or other suitable sealing material is provided between the piston 20 and the cylinder 15 at the forward end of the piston 20.

A piston head is threaded to the forward end of the piston 2t) at threads 28, such piston head 30 forming a part of the piston 2G and being moved therewith. An O-ring seal 28a formed of rubber or similar material is disposed adjacent the threads 28 to provide a uid seal between the piston 20 and the piston head 30. The piston head 30 is recessed as indicated at 30a and is provided with a plurality of lateral openings 36h which are thus in communication with a central longitudinally-extending fluid pressure passage 2Gb extending through the piston 20. The fluid pressure passage 20b communicates with the portion of the cylinder 15 rearwardly of the seal 22 by means of a port 26C. Fluid pressure is introduced into the` bore of the cylinder 15 through an inlet port or passage 15d from a suitable source of hydraulic or other duid pressure (not shown).

The piston head 30 has a knife or cutter blade 32 secured thereto on a specially adapted surface 30C (FIG. 4), and preferably four retaining screws 32a (FIG. 2) are utilized for securing the cutter blade 32 on such surface 30e. The cutter blade 32 is provided with a curved cutting edge 32d which is generally of the radius most suitable for engaging and cutting the typical sizes of tubing T employed in a well.

A second piston 35 which is formed as a sleeve and is slidably disposed within a reduced diameter portion 15e of the cylinder 15 is mounted for limited relative movement longitudinally with respect to the piston head 30 and the piston 20. The bore 35a of the piston 35 is in contact with the external surface of the piston head 30 and a seal 36 formed of rubber or other similar material provides a fluid seal therebetween. A counterbore 35b of the piston 35 is formed to provide a fluid pressure chamber 38 between the first piston 20 and the second piston 35. The laterally-extending ports 30h communicate with the pressure chamber 38 so that the fluid pressure introduced at the inlet 15d ultimately reaches the chamber 38, for a purpose to be hereinafter described. An annular seal or O-ring 39 is disposed between the counterbore 35b and the external surface of the piston head 30 to seal off the pressure chamber 38 together with the seal 36.

On the external surface of the second piston 35, a key 40 is secured by a retaining screw 404e or other suitable means for preventing relative rotation between the sleeve piston 35 and the housing 10. Such key 40 moves in a keyway 4Gb which is formed in the body 10.

A stop pin 42 is threaded in an opening 30d of the piston head 30 preferably into engagement with the upper surface of the cutter blade 32 (FIG. 2) and also extend ing upwardly through a slotted opening 35e in the piston head 35. When the sleeve 35 is in its forward position with respect to the piston 20, the rear end 35d of the slot 35C is in engagement with the pin 42 (FIG. 2), and when the piston 35 is fully retracted inwardly with respect to the piston 20, the forward surface 35e may contact the pin 42. An additional pin 43 may also be provided for limiting rotation of the sleeve 35 with respect to the piston head 30 and thus to the piston 20. Such pin 43 moves in a slot 35i which is similar in shape to the slot 35C, and performs a similar function.

The forward annular surface 35g of the piston 35 is formed with a reduced external diameter. Such surface 35g is adapted to receive a guide element 45 which is curved and mounted on the lower half of the surface 35g by use of mounting screws (not shown) which extend through openings 45a (FIG. 4) and into the metal of the piston 35. Normally, such guide element 45 has a radius of curvature corresponding with the surface 35g and it extends for approximately a 120 arc. The central portion is provided with a curved pipe-engaging surface 45b, the inner portion of whtich is in alignment with the lower curved notch 35h. The guide on the opposite side is on the top side of piston 135. Guides serve to center tubing T and guide it into 45b and 145b. An upper curved notch 35h is also provided in vertical alignment with the lower notch 35h (FIG. 2). The forwardly-extending ears or tips 45e of the element 45 are adapted to extend beyond the tubing T during the cutting thereof for entry into the notch provided at 135g (FIG. 3) of the piston 135 formed on the other side of the cutoff assembly C from the piston 35, as will be ymore evident hereinafter.

For ease of reference, the parts of the right-hand portion of the cutoff assembly C which are illustrated in FIG. 3 have the same numerals as corresponding parts of the left-hand portion of the cutoff assembly C, except that the numeral "l precedes the numerals in FIG. 3 for the right-hand portion parts. It is to be noted that the guide element 145 is on the upper side of the piston 135 so that the guide surfaces 45b and 145b serve to center the tubing T as the knives 32 and 132 move towards each other for cutting. The operation of the right-hand portion of the cutolf assembly C is the same as the operation of the left-hand portion thereof, except that they operate in reverse, both moving towards the pipe or tubing for cutting same and moving away from the pipe or tubing T after cutting and during normal drilling operations.

The blowout preventer B may be of any conventional construction wherein a suitable blind ram can be closed above the knife blades 32 and 132 after the tubing T has been cut. As illustrated in particular in FIGS. 1-3, the blowout preventer B is incorporated with the cutoff assembly C for functioning therewith, both of which may be readily operated hydraulically under normal conditions. Thus, the left-hand portion of the blowout preventer B which is disposed in the cylinder 16 includes a piston 60 which is suitably connected through its piston stem 61 and coupling 62 to a blind ram housing 63 having a resilient ram 64 disposed therein, and a resilient outer seal 65 situated in a groove 63a which extends across the top semiperimeter of ram 63 and longitudinally down the sides and across the face thereof. A blowout preventer of this type is shown in United States Patent No. 2,839,263. The stem 61 with its coupling 62 carry a plunger head 62a which engages a thrust plate `66 disposed adjacent the ram 64 so that as the plunger head 62a moves forwardly, it forces the rubber or other mate- 4 rial of the ram `64 to flow and provide a fluid type seal with the corresponding ram 164 (FIG. 3) of the other portion of the blowout preventer and simultaneously compresses the resilient outer seal 65, thus creating a seal between the upper half of rams 63 and 163 and bore 16C. Hydraulic fluid is introduced through an inlet opening 16a and it may be discharged or relieved through an outlet opening 16b for controlling the position of the piston 60.

In the event the hydraulic system fails, the piston 60 may be moved manually by means of a threaded stem 70 having a handle 75 connected therewith (FIGS. 1 and 2). Also, such stem 70 may be used to lock the piston 60 in the closed or inward position so as to hold the rams 64 and 164 in sealing engagement overnight or during a prolonged period when leakage of the hydraulic fluid may inadvertently occur.

The parts of the right-hand portion of the blowout preventer B bear the same numerals as the corresponding parts of the left-hand portion thereof, except that the numeral "1 precedes the numerals on the right-hand portion. It is to be noted that when the rams 64 and 164 engage each other, they are completely confined by the metal of the holder sleeve L63 and 163 (FIG. 3) and lthey close ofi` the entire opening through the longitudinal bore 10a above the cutter blades 32 and 132. Thus, the blowout preventer B prevents an inadvertent blowout or escape of well fluids after they have been closed, as will be more evident hereinafter.

In the operation or use of the apparatus A of this invention, it is disposed at the wellhead in conjunction with other wellhead equipment so that the tubing T may be passed longitudinally through the longitudinal bore 10a, as illustrated in FIG. 2. During normal conditions of operation, the rams 64 and 164 of the blowout preventer B are in the retracted positions illustrated by the ram 64 l of FIG. 2. Also, during normal operations, the'piston 20 and the piston 35 are in the retractedpositions of FIG. 2 and likewise the corresponding pistons 130 and of the other portion of the cutoff assembly C are in the corresponding retracted position so as to leave a substantially-full open bore through the longitudinal bore 10a for the passage of the tubing T.

Assuming the tubing T is being used for washing out a sanded area down in a well, and it is of the type which is being fed from a reel at the surface, it may become necessary to cut the tubing T in the event a leak develops in the tubing above the wellhead, for example, in the vicinity of a reel upon which the tubing T is wound. When such leak develops in the tubing T, it is extremely important to immediately get the well under control and remove the portion of the` tubing T which has the leak therein. With the present invention, the cutoff assembly C may lbe immediately actuated with hydraulic.

or other pressure fluid introduced through the inlet opening 15d (and the corresponding opening on the other right-hand portion not shown) so as to move the sleeves 35 and 135 inwardly or towards the opening 10a until the stop pins 42 and 142 are engaged by the surfaces 35d and 135d. In such position, fluid pressure has reached the pressure chamber 38 by ow from the inlet through the pistons 20 and 120 and a pressure spring has been created in the areas 381and 138. The fluid spring thus created functions as a spring when the pipe or tubing T is engaged by the surfaces 35h and 45h, as will be more evident hereinafter.

In any event, after the uid pressure in the chambers 38 and 138 have been developed, the duid pressure then acts to move the piston 20 forwardly together with the piston 35 to initially move the surfaces 35h and 45b into engagement with the external surface of the tubing T and to then. cause the knife or cutter element 32 to continue to move inwardly or towards the bore 10a for cutting through the tubing or pipe T. The knife or cutter blade 32 is thus carried by the piston 20 and the piston head 30 and moves inwardly after the piston 35 has been stopped in its inward movement due to the engagement of the surfaces 35h and 45b with the tubing T. The pressure chamber 38 is thus reduced as seen in FIG. 3 and the pressure therein is compressed to provide the resiliency or fluid spring referred to above. The surfaces 35h engage and grip the external surface of the tubing T during the cutting action with the blade 32. It is to be noted that simultaneously with the cutting action vby the blade 32, the blade 132 is cutting the other half of the tubing T so that the tubing T is cut in half or is completely severed by the coaction of the two blades 32 and 132. It is also to be noted that the gripping or stabilizing action obtained during cutting is a function of not only the surfaces 35h and 45t), but also the surfaces 13511 and 145b on the right-hand portion of the cutoff apparaius orassembly C.

During the cutting operation with the cutter blades 32 and 132, the blowout preventer B is in the retracted position of FIG. 2. As soon as the tubing T has been severed, the upper portion of the tubing T is raised as indicated in FIG. 3 so that the lower cut end 8S thereof is above the Iblowout preventer B and then the rams 64 and 164 are caused to close by hydraulic or fluid pressure, or the threading of the stems 7l) from each side of the blowout preventer B. The longitudinal bore 16a is thus completely closed off by the blowout preventer B so that further escape of pressure from the well is prevented by the lowout preventer B. The lower portion of the tubing T, which has been cut from the upper portion thereof, remains in the well below the blades 32 and 132 (FIG. 3).

In order to kill the well to retrieve the lower portion of the tubing or pipe T, mud or other iiuid is pumped into the well at a point below the cutoff assembly C by any valve construction typically used for killirg a well at the wellhead. After the mud has been introduced into the well and the well has been brought under control so that the pressure thereof cannot escape, the knife blades 32 and 132 are retracted `by reversing the operation of the pistons 2t) and 35, or by simply relieving the pressure so that the spring 23 and its corresponding spring on the right-hand portion of the cutoff assembly C function to return them to the retracted position. The blowout preventer B is also returned to its retracted position. The tubing T may then be removed with any suitable iishing or grapping equipment.

The foregoing disclosure and description of the invention are illustrative and explanatory thereof and various changes in the size, shape, and materials, as well as in the details of the illustrated construction, may be made within the scope of the appended claims without departing from the spirit of the invention.

What is claimed is:

1. A cutoff assembly7 for use at wellheads, comprising:

(a) a housing having (l) a wellhead body with a longitudinally-extending bore through which a well pipe or the like is adapted to extend, and

(2) a hydraulic cylinder dispo^ed laterally with respect to said longitudinally-extending bore,

(b) a rst pis'on slidably disposed in said cylinder for movement towards and away from the said bore,

(c) a cutter blade connected to said rst piston for movement therewith for cutting the pipe or the like in the longitudinally-extending bore,

(d) a second piston slidably disposed in said cylinder for movement towards and away from said bore, and

(e) a stabilizer connected to and movable wih said second piston for engagement with the external snrface of the well pipe to stabilize the pipe while cutting same.

2. The structure set forth in claim 1, including:

(a) means for mounting said second piston for limited longitudinal movement relative to said iirst piston, and

(b) means on said first piston and said second piston forming a pressure chamber therebetween for receiving fluid under pressure to create a iiuid spring between the first and second pistons, whereby the stabilizer resiliently engages the well pipe during the cutting action with the cutter blade.

3. The structure set forth in claim 1, including:

(a) means for mounting said second piston for limited longitudinal movement relative to said first piston,

(b) means on said first piston and said second piston forming a pressure chamber therebetween for receiving iiuid under pressure to create a fluid springV between the first and second pistons, wr ereby the stabilizer resiliently engages the weil pipe during the cutting action with the cutter blade,

(c) liuid pressure inlet means in said cylinder for introducing tluid pressure into the cylinder in communication wi h said first piston, and

(d) passage means in said first piston for establishing communication from the fluid pressure inlet means to said pressure chamber.

4. The structure set forth in claim 1, including:

(a) an addiional hydraulic cylinder forming part of said housing and di;posed laterally on the side of said body opposite from said hydraulic cylinder,

(b) a third piston slida'bly disposed in said additional cylinder for movement towards and away from said longitudinally extending bore, and

(c) an additional cutter blade connected to said third piston for movement therewith and for co-action with said cutter blade in cutting the weil pipe or the like in half.

5. The structure set forth in claim 1, including:

(a) an additional hydraulic cylinder forming part of said housing and disposed laterally on the side of said body opposite from said hydraulic cylinder,

(b) a third piston slidably disposed in said additional cylinder for movement towards and away from said longitudinally extending bore,

(c) an additional cutter blade connected to said third piston for movement therewith and for co-action with said cutter blade in cutting the well pipe or the like in half,

(d) a fourth piston slidably disposed in said additional cylinder for movement towards and away 'from said bore, and

(e) an additional stabilizer connected to and movable with said fourth piston for co-acting with said stabilizer -to grip the pipe therebetween while the cutter blades sever the pipe.

6. The structure set forth in claim 5, including:

(a) blowout preventer means with said cutoff assembly for closing the longitudinal bore above the place at which the pipe has been cut by the cutter blade.

7. The structure set forth in claim 1, including:

(a) means for introducing iiuid pressure into said cylinder for moving said first piston and said second piston towards said longitudinally extending bore, and

(b) spring means for moving said rst piston and said second piston in a direction away from said longitudinally extending bore to retract said critter and stabilizer from their positions assumed for cutting the pipe.

8. The structure set forth in claim 1, including:

(a) blowout preventer means with said cutoff assembly.

9. The structure set forth in claim 1, wherein:

(a) said cylinder has a rst bore section in which said first piston is slidably disposed and a second bore section in which said second piston is slidably disposed,

(b) said rst bore section having a smaller diameter than said second `bore section, and

(c) said second piston being formed as a sleeve disposed externally of and slidable relative to said rst piston.

10. The structure set forth in claim 1, wherein:

(a) said cylinder has a rst -bore section in which said rst piston is slidably disposed and a second bore section in which said second piston is slidably disposed,

(b) said first bore section having a smaller `diameter than said second bore section,

(c) said second piston being formed as a sleeve disposed externally of and slidable relative to said first piston,

(d) a pressure chamber dened between said irst piston and said second piston,

(e) a uid pressure inlet in said cylinder for introducing nid pressure,

(f) a passage in said irst piston communicating the fluid pressure inlet with the pressure chamber whereby luid pressure acts on both of the pistons and serves as a uid spring in said pressure chamber.

References Cited UNITED STATES PATENTS 1,802,564 4/1931 Lacey 166-55 X 1,802,565 4/1931 Lacey 166-55 X 1,851,894 3/1932 Clough 166-55 1,875,673 9/1932 Stockstill 166-55 1,949,672 3/1934 Barrier 166--55 2,919,111 12/1959 Nicolson 166 -55 2,969,838 1/1961 Wilde 166--55 JAMES A. LEPPINK, Primary Examiner'. 

1. A CUTOFF ASSEMBLY FOR USE AT WELLHEADS, COMPRISING: (A) A HOUSING HAVING (1) A WELLHEAD BODY WITH A LONGITUDINALLY-EXTENDING BORE THROUGH WHICH A WELL PIPE OR THE LIKE IS ADAPTED TO EXTEND, AND (2) A HYDRAULIC CYLINDER DISPOSED LATERALLY WITH RESPECT TO SAID LONGITUDINALLY-EXTENDING BORE, (B) A FIRST PISTON SLIDABLY DISPOSED IN SAID CYLINDER FOR MOVEMENT TOWARDS AND AWAY FROM THE SAID BORE, (C) A CUTTER BLADE CONNECTED TO SAID FIRST PISTON FOR MOVEMENT THEREWITH FOR CUTTING THE PIPE OR THE LIKE IN THE LONGITUDINALLY-EXTENDING BORE, (D) A SECOND PISTON SLIDABLY DISPOSED IN SAID CYLINDER FOR MOVEMENT TOWARDS AND AWAY FROM SAID BORE, AND (E) A STABILIZER CONNECTED TO AND MOVABLE WITH SAID SECOND PISTON FOR ENGAGEMENT WITH THE EXTERNAL SURFACE OF THE WELL PIPE TO STABILIZE THE PIPE WHILE CUTTING SAME. 